Comorbidity Is the Rule, Not the Exception: Transdiagnostic Approaches to Increase the Effectiveness of Treatment

Introduction: The growth of evidence-based treatment (EBT) has resulted in several efficacious and effective interventions for child psychopathology. However, systematic reviews show that the effect sizes of EBTs range from small to moderate, and they have not increased during the last decades. Many EBTs only address one problem area or diagnosis, while there is compelling evidence to show that comorbidity is the rule, not the exception. Children with comorbidity may not respond well to single-problem EBTs (e.g., parent management training for conduct problems). This shortcoming has been linked to the fact that the classic diagnostic systems do not take the recent discovery of a superordinate and transdiagnostic factor of general psychopathology into account, named the p-factor. This discovery carries the message that EBT can move away from the traditional single-problem approach and address the underlying processes of psychopathology (e.g., emotion regulation). Transdiagnostic treatments offer a single protocol for several problems and diagnoses, and examples of promising transdiagnostic treatments will be presented. Although promising, the transdiagnostic focus in EBT is still in its infancy: We need to learn more about the transdiagnostic core components (i.e., the active ingredients) of treatment.
Methods: First, the presentation will discuss strategies on how to systematically identify, map, and assess transdiagnostic core components. A systematic method of identifying core components based on a broad approach will be presented and where the evidence for each component can be presented in an unbiased manner. Second, the presentation will offer some suggestions on how these transdiagnostic core components can be rigorously evaluated (e.g., time series designs, microtrials and factorial experiments), and on how treatments can be optimized for widespread implementation.
Results: First, preliminary findings of a systematic identification of core components will be provided. Second, examples will be given of how and when core components can be tested and optimized with different designs, before assembled as a transdiagnostic treatment package.
Conclusions: Transdiagnostic treatments have the potential to improve EBTs and thus the outcomes for vulnerable children. The use of systematic methods and rigorous designs may increase the effectiveness of treatments.